Enterprise data centers have a high power consumption which limits the density of servers and increases the total cost of ownership. Power management features have been introduced for server CPUs (central processing units) which provide low power states and dynamic clock and voltage scaling and reduce power consumption significantly during periods when the CPU is idle. There is no such advanced power management, however, for the storage sub-system of a data center and as a result storage uses a significant fraction of the power budget. In an example, a typical enterprise grade disk consumes 12 W even when idle, compared to 24 W for a dual-core processor. As servers typically have many disks, the power consumption due to storage exceeds that of the processors.
The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known data centers and their storage sub-systems.